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Where Fat Comes From

Researchers have found that most fat cells arise from cells in the walls of blood vessels in fat tissue. This insight may lead to new approaches to prevent and treat obesity.

White adipose, or fat, tissue plays a role in regulating our
metabolism, reproduction and life spans. Fat cells form throughout
life, but despite scientists' growing understanding of the roles
these cells play in the body, little has been known about how
they develop.

A research team at the University of Texas Southwestern Medical
Center, led by Dr. Jonathan M. Graff, set out to discover where
fat cells, or adipocytes, come from. Their work, which was funded
by NIH's National Institute of Diabetes and Digestive and Kidney
Diseases (NIDDK), appeared in the October 24, 2008, issue of Science.

The researchers created transgenic mice, putting production
of a marker protein under the control of a known regulator of
fat formation. This allowed them to track when adipocytes form.
By looking at adipose tissue formation, the researchers found
that most adipocytes descend from cells that are committed to
become adipocytes either prenatally or early after birth.

The researchers used proteins expressed on cell surfaces to
identify these precursor cells from adipose tissues. A gene expression
analysis revealed that the cells have a unique molecular signature
that could be used to track and identify them.

To find out where these cells come from, the researchers isolated
sections of adipose tissue. They found that most of the adipocyte
precursors were in the walls of blood vessels. Not all the cells
within blood vessels were adipocyte precursors, and not all the
blood vessels had them. Blood vessels in other tissues didn't
harbor the cells, either.

This research shows that fat cells arise from the network of
blood vessels in adipose tissue. The interplay between this network
and adipocytes may provide potential targets for therapies to
treat obesity. That could have implications for obesity-related
diseases, such as diabetes, heart disease and some cancers.